Offline help installation [closed]

When trying to install offline help (LO 4.2.3.3), I get a message that "This installation package could not be opened. Contact the application vendor to verify that this is a valid Windows Installer package." I've tried downloading with a IE (using both "run" and "save and run" options), Chrome, and Pale Moon (Firefox 64-bit). All my applications are the latest releases, and all patches are applied. System is running Windows 7 64-bit.

Suggestions?

(I've never run into this one before, and have been using LO happily for several years.)